Imagine having no good public transport

You can use liquified hydrogen which need to be chilled and insulated, and will evaporate away in a short time if not properly sealed

Or you use compressed hydrogen which means you are basically carrying an IED that weighs several hundred kilograms with the amount of pressure inside the gas tank

And hydrogen combustion is as others have said, inefficient.

Another issue is that you also need to use basically pure oxygen if you want to use a hydrogen fuel cell, otherwise the catalyst inside the cell would get poisoned

And well, there is a car that did all that, the Toyota Mirai, but that also pretty much ended in commercial failure, due to lack of hydrogen filling infrastructure and a whole load of other reasons.

Well, even though gastric acid(mostly hydrochloric acid) in our stomach does have a relatively low pH, it is very diluted, so in practice it just kills germs and stuff and won’t obliterate everything going inside you

Shift+F10

OOBE/BYPASSNRO

Wait til you get stuck in a traffic jam

Ever heard of domestication?